The water pressure transfer method is the one in which a transfer film having a predetermined water-insoluble print pattern applied onto a water-soluble film is sequentially supplied and floated on a water surface which flows within a transfer tub and made wet with the water and an article (a transferred body or a body to be pattern-transferred) is immersed into the water within the transfer tub while it contacts the transfer film whereby the print pattern of the transfer film is transferred onto the surface of the article using the water pressure to thereby form a decorative layer. In the case where the print pattern is dried, it is required to apply an active agent to the print pattern so as to activate the ink of the print pattern in order to get the same wet state of the ink (the state where it has an adhesion) as the state of the ink immediately after being printed. In order to provide wear resistance, weather resistance (including solvent resistance, chemical resistance, etc.) to the decorative layer formed by transferring the print pattern on the surface of the article, it is necessary to form a transparent surface protection layer (topcoat layer) on the decorative layer.
In one prior art, this surface protection layer is formed by applying by spray an ultraviolet ray hardening type protection coating material onto the decorative layer after transferring the print pattern, removing the water-soluble film out of the surface of the article and drying the article, and then irradiating an ultraviolet ray on the ultraviolet ray hardening type protection coating material to thereby harden the protection coating material.
However, the method of applying the protection coating material on the surface of the article by spray makes difficult the uniform application of the surface protection layer on the whole surface of the article and in addition thereto causes dirt and dust to be adhered onto the decorative layer formed by transferring the print pattern because the protection layer is applied after transferring the print pattern, water-washing and drying the article. Furthermore, since the ultraviolet ray is irradiated onto the protection coating material after removing the article out of an area where the protection coating material is applied, dirt and dust tend to be adhered to the decorative layer, which causes a surface appearance to be deteriorated.
In another prior art JP4-197699A, there has been proposed a method in which water pressure transfer of the print pattern and formation of the surface protection layer are carried out at the same time (see the first patent document). This method is the one in which a transfer film with a protection layer is formed by applying a transparent or semi-transparent surface protection layer of water-insoluble resin on a water-soluble film and then a water-insoluble print layer on the surface protection layer and the transfer film with the protection layer is transferred under water pressure onto an article (a body to be pattern-transferred).
According to this method, since the surface protection layer and the print layer on the water-soluble film are simultaneously transferred on the surface of the article when it contacts the transfer film using water pressure on the water pressure transfer, this method can omit the steps of applying and hardening the protection coating material after the transfer process, which have been required in the first-mentioned conventional art, can avoid dust from adhering between the decorative layer and the surface protection layer and can have little possibility that the thickness of the surface protection layer becomes uneven.
In this manner, this method can be advantageously used because the surface protection layer is formed at the same time when the print layer is transferred whereby the steps of operation can be simplified and in addition thereto the appearance of the decorative layer is never deteriorated and also the surface protection layer can provide wear resistance to the surface of the print layer of the article to thereby physically protect it because the surface protection layer is formed of a protecting agent such as butyl-methacrylate or ethyl-methacrylate, but since the protecting agent has low solvent resistance, when the surface protection layer is dissolved when it contacts various medicines, its surface protection function is reduced and therefore the surface protection layer disadvantageously has the low weather resistance and the poor chemical protection.
There has been proposed another prior art, JP2003-200698A, that is similar to the second prior art, but is different from the latter in that the material for the surface protection layer of the second prior art is replaced by a resin to be hardened by an ultraviolet ray, etc (see the patent document 2).
In the third prior art, since the resin hardened by the ultraviolet ray etc. is used for the surface protection layer, it will physically and chemically protect the decorative layer in an effective manner, but it has some undesirable disadvantages when the adhesion of the print pattern, which is the uppermost surface of the transfer film is recovered or reproduced as described later.
More particularly, although it is common on the aforementioned first to third prior arts, an activating agent or a thinner is applied to the print pattern and also to the surface protection layer (referring to the third prior art) of the transfer film to recover the adhesion of the print pattern and the surface protection layer when the transfer should be carried out, but since the activating agent or the thinner recovers the adhesion of the print pattern by using an organic solvent contained in the activating agent or the thinner, the time in which the solvent ingredient completely volatilizes and the drying condition are required to be considered as the process conditions and a bad influence may be provided to the quality of the water pressure transfer article if the solvent ingredient remains in the print pattern or the surface protection layer. Furthermore, since the organic solvent is emitted into the atmosphere during the operation or inhaled by the human body, using the organic solvent for activating the print pattern or the surface protection layer causes organic air pollution or healthy injury of laborers and this becomes such a problem as should be solved immediately.
As the inventors tried to directly apply such an ultraviolet ray hardening type coating material as used in the first prior art, which is also an eco-friendly coating material, they could discover the recovery of temporary adhesion of the ink in the print pattern of the transfer film, but also find that when it tries in a continuation work during the water pressure transfer process, it becomes poor transfer due to the reduced adhesion of the print pattern. It has been discovered that as the same trial is performed using an ultraviolet ray hardening type ink which contains the same ultraviolet ray hardening resin composite as the ultraviolet ray hardening type coating material does, but contains no coloring agents, the adhesion of the ink in the print pattern can be recovered and that the transfer can be performed without reduction of the adhesion even during the transfer process.
In case of the water pressure transfer, not only the ink in the print pattern has the wet state returned so as to recover the adhesion of the ink, but also the water-soluble film having the print pattern supported thereon is made also wet with the water in the transfer tub whereby both of the print pattern and the water-soluble film are required to be easily attached onto and around the surface of the article when it is forced into the water. Thus, the article should be forced underwater at the time when the harmony of the wet states of both of the print pattern and the water-soluble film is obtained and the adhesion of the print pattern also adapted to attach the print pattern onto the article should be maintained until the transfer is completed.
The inventors believe that the difference between these trial results is caused by the difference between the composition of the ultraviolet ray hardening type coating material and that of the ultraviolet ray hardening type ink as the products different from their usage even though they contain the same ultraviolet ray hardening resin composite. In addition thereto, they believe that there is the difference in that the ultraviolet ray hardening type coating material contains low boiling point solvent, but the ultraviolet ray hardening type ink generally contains less solvent, and therefore, as the ultraviolet ray hardening type coating material is applied to the print pattern, the original adhesion of the print pattern can be recovered by the solvent in the coating material, but the adhesion will be reduced due to the evaporation of the solvent when the transfer is carried out and since the ultraviolet ray hardening type ink has no solvent, any non-solvent composite will serve to recover the print pattern. This invention has been made by repeating various experiments under the aforementioned suppositions.
There will be conceived a method of transferring a surface protection layer on an article under water pressure by using a transfer film having the surface protection layer formed by applying and drying a surface protection agent such as protection coating material or ultraviolet ray hardening resin composite on a water soluble film. However, it is also difficult to form the surface protection layer having all excellent properties of wear resistance, thermal resistance and medicine resistance by this water pressure transfer method and there occurs the same problems as the method of decorating the article by transferring the print pattern on the article when the adhesion of the surface protection layer should be recovered.
An object of the invention is to provide a water pressure transfer method adapted to impart mechanical and chemical surface protection functions, such as wear resistance, solvent resistance, medicine resistance, weather resistance, etc., to a transfer layer such as a decorative layer itself, a surface protection layer or a combination thereof on an article simultaneously with transfer of the transfer layer.
Another object of the invention is to provide a water pressure transfer method adapted to impart mechanical and chemical surface protection functions, such as wear resistance, solvent resistance, medicine resistance, weather resistance, etc., to a surface of an article.
Another object of the invention is to provide a water pressure transfer method adapted to impart sufficient adhesion to an ink of a print pattern of a transfer film without any organic solvent whereby such problems as air pollution due to use of the organic solvent and healthy injury of laborers can be avoided.
Further object of the invention is to provide a water pressure transfer article obtained by imparting surface protection functions of mechanically and chemically protecting a transfer layer such as a decorative layer, a surface protection layer or a combination thereof on the article simultaneously with transfer of the transfer layer.
Further object of the invention is to provide a water pressure transfer article having no dust attached thereto without any problem of air pollution and healthy injury of laborers whereby the article has a good property.
Further object of the invention is to provide a water pressure transfer article having excellent surface protection properties.
Further object of the invention is to provide a water pressure transfer article adapted to have excellent surface protection properties imparted on an article without any problem of air pollution and healthy injury of laborers.